Wind chills hit 15 below zero early Tuesday morning

Scott Dance, The Baltimore Sun

A mass of some of the coldest air to descend on the United States in two decades brought wind chills to as cold as 15 degrees below zero in Baltimore early Tuesday morning, shattering at least one record with more cold lasting into Wednesday.

Temperatures dropped to at least 3 degrees by 6 a.m. at Baltimore-Washington International Thurgood Marshall Airport. With winds gusting to 30 mph, it felt 20 degrees colder. Temperatures were slow to warm through midday, reaching 10 degrees at BWI by noon, with a wind chill of 7 degrees below zero. A wind chill advisory is in effect through 6 p.m.

The cause of the frigid temperatures is a system known as a polar vortex, a swirling column of chilling air over the Arctic that occasionally sends cold spells southward across the United States every winter. This time, the air brought wind chills of 40 degrees below zero at Chicago's O'Hare International Airport and air temperatures of 40 below in Brimson, Minn., on Monday.

"It's brutal out there," AccuWeather.com senior meteorologist Tom Kines said of the north-central United States, noting that conditions in the mid-Atlantic wouldn't be as severe, yet still cause for concern. "The good thing is this is a two-day event. Over the weekend we're going to see temperatures above normal."

Temperatures dropped rapidly Monday night, falling from morning highs in the mid-40s to lows in the single digits by midnight. They kept falling into Tuesday morning, smashing a record low of 8 degrees set in 1988 by at least four degrees.

Colder temperatures were expected to the north and west. Carroll County Regional Airport in Westminster hit 0 degrees by 4 a.m., with wind chills reaching 19 degrees below zero. Garrett County Airport in Western Maryland meanwhile hit air temperatures of 15 below zero with a wind chill of 40 degrees below zero about 5:20 a.m.

Highs Tuesday were expected in the mid-teens in the Baltimore area, threatening a record of 22 degrees set at BWI in 1996. Blustery winds with gusts upward of 30 mph were expected to keep wind chills below zero through Tuesday afternoon, before another chance at single-digit temperatures early Wednesday morning at BWI.

"A lot of that cold is usually blocked up further north," said Brian Lasorsa, a meteorologist with the National Weather Service's Baltimore/Washington forecast office. While the air is normally contained swirling over the North Pole, a weakening in the system that rotates tens of thousands of feet high in the atmosphere can send the cold southward.

Governments around the Baltimore region were readying extra space in shelters and warming centers Monday to prevent weather-related illnesses or deaths.

Baltimore City declared a "Code Blue" advisory to spur canvassing for the homeless and opening of all space in city shelters. The city also opened its emergency operations center to coordinate the response to weather hazards.

Carroll County opened six warming centers and also directed people to public libraries for warmth; Anne Arundel County opened its police stations and libraries and several county churches to those seeking shelter. Maryland Emergency Management Agency officials said they would monitor conditions and shelter capacity to ensure Marylanders aren't left in the cold.

"Overnight services become 24-hour services," said Kris Sharrar, development director for the Helping Up Mission. The faith-based shelter for men in East Baltimore was expected to serve 100 extra meals on top of the 1,000 it normally serves daily, Sharrar said.

The last time subzero temperatures hit the region, in February 1996, ice floes as much as a foot thick trapped residents of Chesapeake Bay islands for days. Ron Houck, a waterways specialist for the U.S. Coast Guard Sector Baltimore, said the agency was monitoring reports of ice but had not heard of any significant freezes by Monday.

Temperatures took a wide swing at BWI on Monday, from the day's high in the mid-40s in the early morning to lows in the single digits, though more dramatic shifts have been recorded. In early January 1979, the airport hit a record high of 64 degrees one day and a record low of 10 degrees the next, 19 1/2 hours apart.

Any freezing that occurs is likely to thaw by the weekend, with highs forecast to reach 40 degrees by Friday and the 50s Saturday.